Delivery catheter

ABSTRACT

A medical catheter for the transvascular deployment of a collapsible medical device such as a filter has a tubular body formed by an inner tubular core surrounded by an outer thin-walled tube which is fixed to the core. The outer thin-walled tube extends outwardly beyond a distal end of the core to form a fixed thin-walled medical device embracing pod. The filter is carried on a guidewire which is slidably engagable within a central lumen of the core and the filter can be collapsed against the guidewire for loading within the pod. With the filter thus loaded within the pod the distal end of the catheter can be maneuvered through a patient&#39;s vascular system to a desired deployment site where the filter is discharged from the pod allowing the filter to expand within the blood vessel for use filtering blood flowing through the blood vessel.

This is a divisional of application Ser. No. 10/727,986 filed Dec. 5,2003, which is a Continuation Application of U.S. application Ser. No.09/676,468 filed Oct. 2, 2000 (now U.S. Pat. No. 6,752,819), which is aContinuation Application of PCT Application No. PCT/IE99/00021 filedApr. 1, 1999, and claims priority of Ireland Application No. 980242,filed on Apr. 2, 1998. The entire disclosures of the prior applications,application Ser. Nos. 10/727,986, 09/676,468, PCT/IE99/00021 and 980242are incorporated herein.

FIELD OF THE INVENTION

The present invention relates to a medical catheter and moreparticularly to a catheter for the transvascular deployment ofexpandable medical devices, such as an intravascular embolic filterdevice, in a collapsed condition.

BACKGROUND OF THE INVENTION

The device as described herein relates to a carotid angioplastyprocedure with an intravascular filter being placed distally to captureprocedural emboli being released. Other medical procedures warrant theuse of distal protection systems. Angioplasty and stenting of surgicallyimplanted Saphenous Vein grafts that have stenosed and primary treatmentof Renal artery stenoses are applicable also. Indeed, the insertion ofembolic protection devices to protect patients during any vascularsurgery is envisioned as being applicable to this invention.

A particularly useful form of embolic protection device in the form of afilter element for placing in a desired position has been described inour co-pending Patent Application No. PCT/IE98/00093 the contents ofwhich are incorporated herein by reference. For example, this filterelement is compressed into a housing or pod to advance it to therequired location in a vessel. Once in situ the housing is withdrawn orthe filter element is advanced. This allows the compressed filterelement to expand to the required size and occlude the vessel except forthe path or paths provided through the filter which thus provides apathway for blood and has means for capturing and retaining undesiredembolic material released during the surgical operation or percutaneousinterventional procedure.

There are difficulties with such expandable devices, whether they befilters or other devices in that firstly they have to be correctly andefficiently compressed and retained within the pod so that when releasedfrom the pod, they will expand to assume the correct shape and will nothave been distorted by the compression within the pod. The problems ofdistortion or incorrect expansion tend to be exacerbated if the medicaldevice is stored for long periods within the pod prior to use. Secondly,it is important that the pod and the catheter tube itself be manipulatedto the site of use without causing damage to, for example, the arteriesthrough which it is being manipulated. Difficulties may arise if, forexample, the catheter tube, or more particularly the pod as the podeffectively leads in the insertion, were to damage the artery sidewalland thus cause for example a break-away of atherosclerotic plaque fromthe carotid arteries.

Essentially this leads to certain requirements. The device needs to beefficiently compressed. The resulting compressed device needs to bemanipulated in its pod as efficiently as possible. Further, there is aneed for loading such catheters in a way that will facilitate their useon unloading.

It is known to mount implantable medical devices at a distal end of adelivery catheter for transvascular deployment. Upon reaching a desiredlocation within a patient's vasculature the catheter is withdrawnrelative to the medical device thus allowing the medical device toexpand or be expanded within the blood vessel. In the prior art WO98/07387 and U.S. Pat. No. 5,064,435 show stent delivery systemsessentially comprising a catheter with a stent mounted in a collapsedstate at a distal end of the catheter under a retractable outer sheath.An abutment within the bore of the catheter spaced proximally from thedistal end of the catheter prevents retraction of the stent as the outersheath is withdrawn over the stent. Each of these devices has at leasttwo main components, namely an inner catheter and an outer sheath whichis slidably retractable on the catheter to expose the stent fordeployment.

These deployment catheters need to have lateral flexibility in order tomaneuver through the vasculature but at the same time be sufficientlypushable so that they can be steered and manipulated through thevasculature. The mounting of a medical device within the distal end ofthe catheter either greatly limits the size of the medical device thatcan be accommodated or necessitates enlargement of the catheter whichrestricts access of the catheter within the vasculature of a patient.

Catheters of this type tend to be relatively long and the loading of amedical device within the distal end of the catheter prior to use can bea somewhat cumbersome operation for the surgeon. The length of thecatheters makes them unwieldy and difficult to keep sterile. There isalso a difficulty in ensuring air is excluded from the medical deviceand catheter during loading.

The present invention is directed towards overcoming these problems.

SUMMARY OF THE INVENTION

According to the invention there is provided a catheter for thetransvascular deployment of a medical device, the catheter comprising anelongate tubular body having a proximal end and a distal end, a tubularhousing being formed at the distal end of the body for reception of themedical device, a deployment means for engagement with the medicaldevice, being movable through the housing to move the medical devicebetween a stored position within the housing and an in-use positionexternally of the housing, characterized in that the housing comprises atubular thin-walled medical device embracing pod fixed at the distal endof the body, the pod extending outwardly from the distal end of the bodyand forming an extension thereof. Conveniently, the pod and the catheterbody form a single integral unit for deployment of the medical device.

Preferably the catheter body has an inner tubular core encased within aconcentric thin-walled tubular outer sheath which is fixed to the core,the sheath being extended outwardly of a distal end of the core to formthe pod.

The advantage of using the thin-walled tube is that the maximum volumeto retain the medical device for deployment is achieved. Further the podis relatively flexible on the catheter further facilitating itsmanipulation and passage through vasculature to the desired site of use.

Preferably the inner tubular core is formed from a steel spring, but mayalternatively be formed from polymeric material. Any suitable materialmay be used as the core is now covered by the thin-walled tubular outersheath which is effectively the important tube, being the vessel contactsurface. Alternatively, a thin walled pod may be achieved by locallythinning a polymeric tube at the distal end of the tube.

Preferably the thin-walled tube is manufactured from a low frictionmaterial and ideally is manufactured from polytetrafluoroethylene (PTFE)often sold under the Registered Trade Mark TEFLON. The thin walled tubemay alternatively be manufactured from any other suitable thin walledmaterial of low friction coefficient or employing a friction reducingagent or component to minimize the friction coefficient. The advantageof this is that firstly the catheter will not damage arteries, forexample the carotid, knocking off atherosclerotic plaque. Further thiswill allow the easy removal of the implant from the catheter.

Where the outer thin walled tube is formed of PTFE, it would typicallyhave a thickness of less than 0.004 inches. The thickness of thin walledtubes of other materials may vary somewhat depending on thecharacteristics of the material being used.

In another aspect the invention provides a method of loading such acatheter comprising:

inserting a loading tube into the pod at a free end of the outerthin-walled tube; and

compressing the medical device and delivering the compressed medicaldevice through the loading tube into the pod.

The problem is that if one did not insert the loading tube into the podthe thin-walled tube would collapse in compression when trying to insertthe medical device. The use of the loading tube prevents such collapse.

Preferably the loading tube is a further thin-walled tube which isinserted into the pod for smooth delivery of the medical device into thepod.

Ideally the medical device is compressed by delivering the filter devicethrough a funnel and into the loading tube which is mounted at an outletof the funnel.

In another aspect the invention provides a delivery system fortransvascular deployment of a medical device, the system comprising acatheter in combination with an associated separate loading device whichis operable to collapse the medical device from an expanded in-useposition to a collapsed position for reception within the pod.

Preferably the loading device comprises means for radially compressingthe medical device.

In a particularly preferred embodiment the loading device comprises afunnel having an enlarged inlet end and a narrowed outlet end, theoutlet end being engagable within the pod.

In another embodiment, the loading device comprises a main supporthaving a funnel-shaped bore formed from a frusto-conical filter devicereceiving portion terminating in a cylindrical portion formed by athin-walled loading tube projecting from the main support. Thisfunnel-like arrangement is a very suitable arrangement of loading a podon the catheter with a compressible filter device.

Ideally the cone angle is between 15° and 65° and preferably may bebetween 35° and 45°. This allows a sufficiently gentle compression of afilter device, particularly one of a polymeric material.

In one particularly preferred embodiment of the invention, the mainsupport, is formed from perspex and the thin-walled loading tube isformed from PTFE material. The perspex gives a smooth surface.

Preferably the loading tube is mounted on the main support on a metalspigot at an outlet end of the funnel.

In a still further aspect the invention provides a pack for an elongateintravascular catheter of the type comprising a tubular body with aproximal end and a distal end, the distal end adapted for reception of amedical device, the pack comprising a tray having means for releasablyholding the distal end of the catheter relative to an associatedcatheter loading device in a cooperative juxtaposition on the tray, theloading device being operable to collapse the medical device from anexpanded in-use position to a collapsed position for reception withinthe pod. This facilitates raid and correct loading, of a medical devicewithin the catheter.

Preferably the tray has a liquid retaining bath formed by recess in thetray, the bath having a depth sufficient to accommodate in a totallysubmerged state the distal end of the catheter and a medical device forsubmerged loading of the medical device into the catheter.

In another embodiment the tray has a catheter holding channelcommunicating with the bath, the channel defining a pathway around thetray which supports the catheter in a loading position on the tray.

Preferably the means for securing the catheter within the channelcomprises a number of retainers spaced-apart along the channel, eachretainer comprising two or more associated projections which projectinwardly from opposite side walls of the channel adjacent a mouth of thechannel, the projections being resiliently deformable for snapengagement of the catheter within the channel behind the projections.

Conveniently a ramp is provided at an end of the channel communicatingwith the bath to direct a distal end of the catheter towards a bottom ofthe bath.

In another embodiment means is provided within the bath for supportingthe distal end of the catheter above the bottom of the bath. Preferablysaid supporting means is a step adjacent the channel.

In another embodiment means is provided within the bath for supporting acatheter loading device for engagement with the distal end of thecatheter to guide a medical device into the distal end of the catheter.Preferably said means comprises a recess in a side wall of the bath forreception of a funnel with an outlet pipe of the funnel directed towardsthe channel for engagement within the distal end of the catheter.

Ideally, it will be appreciated that the device for loading the catheterwith a compressible filter device such as described above may be used inconjunction with this pack. The advantage of this is that the filterdevice can be submerged in a saline bath during loading into the podwhich ensures that air is excluded from the filter device when loadingas it would obviously cause medical complications if air was introducedto the bloodstream during an angioplasty and stenting procedure.

The tray system with the catheter distal end submerged, combined withappropriately designed catheter proximal end and standard deviceflushing techniques can ensure a fluid filled device is introduced tothe vasculature.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the followingdescription of some embodiments thereof, given by way of example only,with reference to the accompanying drawings, in which:

FIG. 1 is a perspective diagrammatic view of a catheter assemblyaccording to the invention,

FIG. 2 is a detail partially sectioned elevational view showing anexpandable filter device loaded into a distal end of the catheter,

FIG. 3 is a sectional view showing a distal end portion of the catheterand a loading device for use with the catheter,

FIG. 4A is a detail sectional elevational view of the distal end portionof the catheter,

FIG. 4B is a view similar to FIG. 4A showing another catheterconstruction,

FIG. 4C is a view similar to 4A showing another catheter construction,

FIG. 5 is a detail diagrammatic partially sectioned perspective viewshowing the distal end of the catheter about to be loaded,

FIG. 6 is a detail sectional elevational view showing the distal end ofthe catheter loaded with the loading device still in position,

FIG. 7 is a detail sectional elevational view of a filter device for usewith the catheter shown in an expanded in-use position;

FIG. 8 is a sectional view of portion of the loading device,

FIG. 9 is a plan view of a pack for holding the catheter assemblyaccording to the invention,

FIGS. 10A and 10B are detail plan views of retaining clip portions ofthe pack of FIG. 9,

FIG. 11 is a perspective view showing a bath portion of the pack of FIG.9, and

FIG. 12 is a sectional view of the bath portion of the pack illustratedin FIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings and initially to FIGS. 1 and 2 thereof, thereis illustrated a catheter, indicated generally by the reference numeral1, for mounting a collapsible filter 2 or other collapsible medicaldevice. The catheter has on its free distal end a pod 3 within which thefilter 2 is shown compressed in FIG. 2. A guide wire 6 on which thefilter 2 is mounted is also illustrated in FIG. 2.

FIG. 7 shows the collapsible filter device 2, of the type described inour Patent Application No. PCT/IE98/00093, in an expanded in-useposition. The filter device 2 is mounted adjacent a distal end of theguidewire 6 which terminates at the distal end in a flexible spring tip7.

The filter device can be collapsed inwardly against the guidewire 6 forreception within the pod 3 as shown in FIG. 2.

Referring particularly to FIGS. 2, 3 and 4A the catheter 1 comprises anouter thin walled tube 10 of PTFE or other thin walled polymer tubesurrounding an elongate tubular body forming an inner support core whichin this embodiment is formed by a spring 11. The outer thin wall tube 10projects beyond a distal free end 12 of the spring 11 to form the pod 3.

An alternative catheter construction is shown in FIG. 4B. In this casethe catheter 1 is formed by a polymeric tube body 14 having athin-walled distal end portion 15 which forms the pod 3. Thisthin-walled pod 3 is formed by locally thinning the polymeric tube body14 at the distal end 15 of the tube body 14. A still furtherconstruction is shown in FIG. 4C in which in this case the inner supportcore is formed from polymeric tubing 16.

FIG. 3 also illustrates a loading device indicated generally by thereference numeral 20, which loading device comprises a support 21 havinga funnel-shape bore 22 formed from a frusto-conical filter devicereceiving portion 25 terminating in a cylindrical portion formed by athin wall stainless steel spigot 23 on which is mounted a loading tube24, again of a flexible thin wall material, in this embodiment PTFE. Itwill be seen from FIG. 3 how the loading device 20 is inserted into thepod 3.

To use the loading device 20, referring now specifically to FIGS. 5 and6, the filter 2 is connected to the guidewire 6 and is drawn through theloading device 20 where it is compressed and pulled through the spigot23 and the loading tube 24 until it rests within the pod 3 at a proximalend of the pod 3. With the guidewire 6 held fast relative to thecatheter, the loading device 20 is withdrawn leaving behind the filter 2which is now mounted within the pod 3 as shown in FIG. 2. It will beappreciated that the filter device 2 will move smoothly through theloading tube 24 as the loading tube 24 is in tension during loading.

The catheter 1 can then be delivered trans-arterially according tostandard clinical practice to a deployment site. As the catheter 1 ismoved through the arteries a leading end of the pod 3 which is flexiblewill deflect to assist in guiding the catheter 1 to the deployment sitewithout damaging the artery wall. Once in position the filter device 2is held stationary whilst catheter body incorporating the pod 3 isretracted. When released the filter device 2 will expand to fill thevessel.

Advantageously for use simply as a deployment catheter the thickness ofthe pod wall can be minimized, and consequently the crossing profile ofthe catheter can be minimized, as the pod does not need to be able towithstand compressive forces which would collapse the pod. Whenretaining the medical device and when pushing the medical device out ofthe pod for deployment the pod wall is in tension and so will notcollapse. For loading the medical device in the pod the loading tube ofthe loading device projects into the pod to shield the pod fromcompressive forces which would collapse the pod.

It will be appreciated that instead of having the guidewire co-axiallymounted within the catheter along the full length of the catheter, theguidewire may only be co-axial with an outer free end of the catheter.In this case, the guidewire is mounted alongside the catheter and entersan inlet hole adjacent the outer free end of the catheter (typically5-20 cm from the end of the catheter) to travel coaxially within theouter free end of the catheter. This configuration is commonly referredto as a RAPID EXCHANGE system.

It will be appreciated that the catheter/pod assembly may be constructedwith a single polymeric tubing that has an integral distal thin walledsection describing the pod. This construction can be achieved by alocalized molding operation. Alternatively, a pod may be bonded to theproximal tube by way of adhesive or welding.

The pod described in any of the constructions may be fabricated withenough longitudinal stiffness such that it can withstand compressiveloading of a filter element into it. In this embodiment the deliverycatheter may also be used as a retrieval catheter.

Referring now specifically to FIGS. 9 to 12, there is illustrated a packfor retaining a catheter assembly. Such a catheter assembly could be ofconventional construction or may be as is illustrated, a catheter 1according to the present invention.

Referring to FIGS. 9 and 10 initially, the pack has a molded plasticstray 30 which is recessed to support the parts of a catheter such as,for example, a recess 31 to retain a conventional Y-connector with anassociated hub receiving slot 32 at one end for reception of a hubmounted at a proximal end of a catheter. A bath 33 is formed by anotherrecess in the tray 30. A catheter mounting recess or channel 34 extendsbetween the hub receiving slot 32 and the bath 33. It will be noted thatthe channel 34 is shaped to define a desired curve with no sharp bendsand smooth transitions to facilitate loading of a catheter in situ. Thechannel 34 is provided with a number of spaced-apart retaining clips 37illustrated in FIG. 10. Each retaining clip 37 comprises threeassociated projections 42 which project inwardly from opposite sidewalls 43 of the channel 34 adjacent an upwardly open mouth of thechannel 34. These projections 42 and/or the side walls 43 of the channel34 are resiliently deformable for snap engagement of a tubular catheterbody within the channel 34 behind the projections 42. A downwardlysloping ramp 44 (FIG. 12) is provided at an end of the channel 34communicating with the bath 33 to direct a distal end of a catheter 1towards a bottom of the bath 33. Further recesses 39 and 40 respectivelyare provided to retain an adapter and a syringe for flushing thecatheter 1 with saline solution. Obviously, it will be appreciated thatmany other forms of apparatus could be provided.

The bath 33 has a bottom 45 with an upwardly extending side wall 46. Itwill be noted that a step 47 is provided adjacent the channel 34 forsupporting the distal end of the catheter 1 above the bottom 45 of thebath 33 to facilitate loading of the catheter 1 with a medical device 2.

A recess 48 is shaped in the step 47 for reception of the loading device20 for the catheter 1. When the loading device 20 is mounted in therecess 48 the loading tube 24 extends into the pod 3 of the catheter 1in a cooperating loading position. Lugs 49 at each side of the recess 48engage and retain the support 21 in the recess 48. These lugs 49 areresiliently deformable for snap engagement of the support 21 in therecess 48 and to allow release of the support 21 from the recess 48.

A further channel 50 for a balloon tube is also provided on the tray 30having a number of spaced-apart retaining projections 52 (FIG. 10) toretain a balloon tube in the channel 50. In use, the catheter 1 ispackaged on the tray 30, being mounted within the channel 34 so it isheld on the tray 30 in a position ready for loading. Saline solution isinjected through the catheter 1 to exclude air from the catheter 1 andthe bath 33 is filled with saline solution. The guidewire 6 having thefilter 2 attached is then fed through the loading device 20 and throughthe catheter 1. Air is excluded from the filter 2 which is submerged inthe saline bath and the filter 2 is then drawn through the loadingdevice 20 into the pod 3 at the distal end of the catheter 1. Theloading is conducted under water to prevent air entrapment in the filterdevice 2 whilst loading the filter device 2 in the pod 3 at the distalend of the catheter 1. It will be noted that the pod 3 at the distal endof the catheter 1 is submerged and, the catheter 1 is held firmly on thetray in loading engagement with the loading device 20 while the filter 2is being loaded into the pod 3.

The invention is not limited to the embodiments hereinbefore describedwhich may be varied in both construction and detail within the scope ofthe appended claims.

1-28. (canceled)
 29. A medical catheter pack for a delivery system, thepack comprising: a delivery system comprising: a catheter comprising: anelongate catheter tubular body having a proximal end and a distal end, atubular medical device embracing pod located at the distal end of thecatheter tubular body for reception of the medical device, the pod beingintegrally formed with the catheter tubular body and including athin-walled distal portion of the catheter tubular body of reduced wallthickness relative to a proximal portion of the catheter tubular body,and the pod having a greater flexibility than the proximal portion ofthe catheter tubular body, and a deployer movable through the pod tomove the medical device between a stored position within the pod and anin-use position externally of the pod; an associated separate loadingdevice which is operable to collapse the medical device from an expandedin-use position to a collapsed position for reception within the pod;and a tray configured to releasably hold the pod of the catheterrelative to the associated separate loading device in a cooperativejuxtaposition on the tray.
 30. A pack as claimed in claim 29 wherein thetray has a liquid retaining bath formed by a recess in the tray, thebath having a depth sufficient to accommodate in a totally submergedstate the pod of the catheter and the medical device for submergedloading of the medical device into the pod.
 31. A pack as claimed inclaim 30 wherein the tray has a catheter holding channel communicatingwith the bath, the channel defining a pathway around the tray whichsupports the catheter in a loading position on the tray.
 32. A pack asclaimed in claim 31 wherein the catheter is held within the channel by anumber of retainers spaced apart along the channel, each retainercomprising two or more associated projections which project inwardlyfrom opposite side walls of the channel adjacent a mouth of the channel,the projections being resiliently deformable for snap engagement of thecatheter within the channel behind the projections.
 33. A pack asclaimed in claim 31 wherein a ramp is provided at an end of the channelcommunicating with the bath to direct the pod of the catheter towards abottom of the bath.
 34. A pack as claimed in claim 33 including a stepadjacent the channel configured to support the pod of the catheter abovethe bottom of the bath.
 35. A pack as claimed in claim 30 wherein arecess provided within the bath supports the catheter loading device forengagement with the pod of the catheter to guide the medical device intothe pod of the catheter.
 36. A pack as claimed in claim 35 wherein saidrecess is located in a side wall of the bath for reception of a funnelwith an outlet pipe of the funnel directed towards the channel forengagement with the pod of the catheter.
 37. A method for preparing amedical catheter for the transvascular deployment of a medical device,the method comprising the steps of: providing a medical cathetercomprising: an elongate tubular body having a proximal end and a distalend, a tubular medical device embracing pod located at the distal end ofthe catheter tubular body for reception of the medical device, the podbeing integrally formed with the catheter tubular body and including athin-walled distal portion of the catheter tubular body of reduced wallthickness relative to a proximal portion of the catheter tubular body,and the pod having a greater flexibility than the proximal portion ofthe catheter tubular body, and a deployer movable through the pod tomove the medical device between a stored position within the pod and anin-use position externally of the pod; providing a loading device forcollapsing the medical device from an expanded in-use position to acollapsed position for reception within the pod, the loading devicehaving an inlet end and an outlet end; engaging the outlet end of theloading device within the pod; engaging the medical device with thedeployer; retracting the deployer proximally through the cathetertubular body, to draw the medical device through the loading device intothe pod, thereby collapsing the medical device; and disengaging theloading device from the pod.
 38. A method for deploying a medical deviceat a desired location in a vasculature, the method comprising: providinga medical catheter comprising: an elongate tubular body having aproximal end and a distal end, and a tubular medical device embracingpod located at the distal end of the catheter tubular body for receptionof the medical device, the pod being integrally formed with the cathetertubular body and including a thin-walled distal portion of the cathetertubular body of reduced wall thickness relative to a proximal portion ofthe catheter tubular body, and the pod having a greater flexibility thanthe proximal portion of the catheter tubular body; loading the medicaldevice into the pod of the medical catheter; inserting the medicalcatheter into a vasculature and advancing the medical catheter throughthe vasculature until the pod is in a desired location; and deployingthe medical device from the pod at the desired location.
 39. A method asclaimed in claim 38 wherein the loading of the medical device into thepod includes engaging the medical device with a deployer and retractingthe deployer proximally to draw the medical device into a loading devicecoupled to the pod.
 40. A method as claimed in claim 39 wherein theloading device collapses the medical device from an expanded in useposition to a collapsed position for reception within the pod.
 41. Amethod as claimed in claim 40 wherein the loading device comprises afunnel having an enlarged inlet end and a narrowed outlet end, theoutlet end being engagable within the pod.
 42. A method as claimed inclaim 38 wherein the medical device is deployed by moving the cathetertubular body proximally relative to the deployer.
 43. A method asclaimed in claim 38 including withdrawing the catheter tubular body fromthe vasculature after deploying of the medical device.
 44. A method asclaimed in claim 38 wherein the medical device is a filter device.